THE EXTERNAL

MORPHOLGYE OF
THE
TELENCEPHALON

Prof. Dr Branislav
Filipovic
 Brain orientation

• Rostral-caudal*
• Anterior-posterior
• Dorsal-ventral*
• Superior-inferior
• Medial-lateral
• * change from
brainstem-spinal
cord (13.1)
 Brain orientation

• Rostral = anterior
• Caudal = posterior
• Dorsal = superior
• Ventral = inferior
 Brain ventricles
• Cavities in brain
• Develop from
neural tube
• Contain CSF
• Lined by
ependymal cells

(13.6b)
Coronal Brain
Slice
 Brain ventricles

• Lateral ventricles
(#1&2)
• Third ventricle
• Cerebral aqueduct
• Fourth ventricle
• Central canal
(13.6b)
 Lateral ventricles
• From telencephalon
• Within cerebral hemispheres
• “C” shaped

(13.6ab)
Frontal pole 2. Superior frontal sulcus 3. Middle frontal gyrus 4. Superior
frontal gyrus 5. Precentral sulcus 6. Longitudinal cerebral fissure
7. Precentral gyrus 8. Postcentral gyrus 9. Central sulcus 10. Postcentral
sulcus 11. Occipital pole
1. Superior frontal gyrus 2. Superior frontal sulcus 3. Central sulcus
4. Precentral gyrus 5. Postcentral gyrus 6. Supramarginal gyrus 7.
Angular gyrus 8. Postcentral sulcus 9. Parieto-occipital sulcus 10.
Superior parietal lobule 11. Intraparietal sulcus 12. Precentral sulcus
13. Middle frontal gyrus 14. Inferior frontal sulcus 15. Inferior frontal
gyrus 16. Anterior ascending ramus of lateral sulcus 17. Transverse
temporal gyrus 18. Anterior horizontal ramus of lateral sulcus 19.
Superior temporal gyrus 20. Superior temporal sulcus 21. Middle
temporal gyrus 22. Stem of lateral sulcus 23. Inferior temporal
sulcus 24. Inferior temporal gyrus 25. Preoccipital notch 26.
Posterior branch of lateral sulcus 27. Triangular part of inferior
frontal gyrus 28. Opercular part of inferior frontal gyrus
1. Medial frontal gyrus 2. Cingulate sulcus 3. Cingulate gyrus 4. Central
sulcus 5. Paracentral lobule 6. Callosal sulcus 7. Isthmus of cingulate
gyrus 8. Subparietal sulcus 9. Precuneus 10. Parieto-occipital sulcus
11. Cuneus 12. Calcarine sulcus or fissure 13. Rostrum of corpus
callosum 14. Genu of corpus callosum 15. Trunk of corpus callos 16.
Splenium of corpus callosum 17. Choroid plexus in interventricular
foramen 18. Interthalamic adhesion 19. Habenular trigone 20.
Hypothalamic sulcus 21. Pineal body 22. Anterior (rostral) commissure
23. Tectum of midbrain 24. Mamillary body 25. Medial longitudinal
fasciculus 26. Choroid plexus of 4th ventricle
1. Frontal pole of left cerebral hemisphere 2. Olfactory bulb 3. Olfactory tract 4. Orbital gyri and
sulci 5. Straight gyrus 6. Temporal pole of left cerebral hemisphere 7. Olfactory trigone 8. Optic
nerve 9. Optic chiasma 10. Anterior (rostral) perforated substance 11. Optic tract 12. Tuber
cinereum with infundibulum 13. Oculomotor nerve 14. Mamillary body 15. Uncus of
parahippocampal gyrus 16. Basis pedunculi 17. Basilar sulcus of pons 18. Trigeminal nerve 19.
Abducens nerve 20. Pyramid of medulla oblongata 21. Facial nerve 22. Vestibulocochlear nerve 23.
Glossopharyngeal nerve 24. Vagus nerve 25. Cranial roots of accessory nerve 26. Spinal roots of
accessory nerve 27. Rootlets of hypoglossal nerve 28. Flocculus 29. Ventral rootlets of 1st cervical
spinal nerve 30. Pyramidal decussation
1. Olfactory bulb 2. Orbital sulci and gyri 3. Olfactory tract 4. Gyrus rectus 5.
Olfactory trigone 6. Optic chiasma 7. Tuber cinereum with infundibulum 8.
Mamillary body 9. Posterior (interpeduncular) perforated substance 10. Basis
pedunculi 11. Substantia nigra 12. Superior cerebellar peduncle 13.
Mesencephalic (cerebral) aqueduct 14. Pineal body 15. Splenium of corpus
callosum 16. Rhinal sulcus 17. Parahippocampal gyrus 18. Medial
occipitotemporal gyrus 19. Lateral occipitotemporal gyrus 20. Collateral sulcus 21.
Occipitotemporal sulcus 22. Lingual gyrus
 Cerebral
hemispheres
• Landmarks
• Lateral fissure
• Longitudinal
fissure (13.4)
• Sulci (sulcus) –
grooves
• Gyri (gyrus) –
ridges
• Central sulcus
13.7c
 Frontal lobe
• Anterior/rostral to central sulcus
• Superior to transverse/lateral
fissure

(13.7abc)
 Parietal lobe
• Posterior to central sulcus
• Superior to lateral fissure
• Anterior to parieto-occipital sulcus

(13.7abc)
 Temporal lobe
• Inferior to lateral fissure
• Anterior to occipital lobe

(13.7abc)
 Occipital lobe
• Posterior & inferior to parieto-
occipital sulcus
• Posterior to temporal lobe

(13.7abc)
1. Anterior (rostral) commissure 2. Cut surface of parahippocampal
gyrus 3. Amygdaloid body 4. Column of fornix 5. Mamillary body 6.
Tail of dentate gyrus 7. Inferior surface of corpus callosum 8. Body of
fornix 9. Dentate gyrus 10. Fimbria of hippocampus 11. Crus of fornix
12. Deep cortex of parahippocampal gyrus 13. Commissure of fornix
14. Choroid plexus in temporal horn of lateral ventricle 15. Splenium
of corpus callosum 16. Gyrus fasciolaris
1. Short association (arcuate) bundles 2. Superior longitudinal
fasciculus 3. Short gyri of insula 4. Inferior occipitofrontal
fasciculus 5. Central sulcus of insula 6. Limen insulae 7. Long
gyrus of insula 8. Inferior longitudinal fasciculus
 Cerebral cortex

• Gray matter - ~2-4 mm

thick
• White matter
– Fiber tracts
– Myelinated axons

(13.8)
 Brodmann areas
• Cytoarchitectonics (light microscopy)
• Early 1900s
• Areas 1-52
(13.10ab)
 1° Motor cortex

• Brodmann area 4
• Precentral gyrus (frontal lobe) (13.10ab)
 1° Motor cortex

• Pyramidal neurons
• UMN = upper motor
neuron

[silver stain of UMNs

in motor cortex]
http://www.meddean.luc.edu/lumen/MedEd/Histo/frames/h_frame6.html
 1° Motor cortex

• Motor homunculus
– somatotopy
• Project contralaterally
• Controls fine motor
movement
– Forearm, fingers, face

(13.11)
Note R/L
 Sensory cortices
• 1° Sensory cortices
– First cortical areas to receive sensory
signals
– First conscious awareness of sensations
– Organized by modalities, e.g., vision,
touch, hearing, etc.
• Association Sensory Cortices
– Close to 1° sensory cortices
– Information processing
– Interpretation of sensations
– Memory of sensations
 1° Somatosensory cortex

• Brodmann areas 3,1,2

• Postcentral gyrus (parietal lobe)
• Modalities: touch, pain, pressure,
vibration, temperature, conscious
proprioception

(13.10ab)
 1° Somatosensory cortex

• Sensory homunculus
• Contralateral
• Spatial discrimination
(localization)
• Cortical enlargement

(13.11)
 Somatosensory
association cortex
• Brodmann areas 5 & 7 (parietal lobe)
• Stereognosis – recognition by touch
– Sensory integration
– Memory
– Astereognosis – damage to area

(13.10ab)
 1° Visual (striate) cortex
• Brodmann area 17
• Calcarine sulcus
• Contralateral visual field

(13.10ab)
 Visual association areas
• Brodmann areas 18,19+
• Occipital, parietal, temporal lobes
• Visual information processing
– Color, form, motion

(13.10ab)
 1° Auditory cortex
• Brodmann areas 41 & 42
• Temporal lobe
• Inferior lip of lateral fissure

(13.10a,13.8)
 Auditory association
areas
• Brodmann area 22
• Posterior to 1° auditory cortex
• Interpretation of sounds
– Meaning
– Significance
– Sound memory

(13.10a)
 Wernicke’s area
• Dominant side
• Language comprehension

(13.10a)
 Wernicke’s aphasia
• The speech impairment when a
patient is not able to understand
the words or sentences heard
• Mostly of vascular origin
Other sensory cortices
• Gustatory cortex
• Vestibular cortex
• Olfactory cortex
 Cerebral white matter

• Fiber tracts –
functionally &
structurally related
bundles of axons
(nerves in PNS)
• Deep to cerebral
cortex
• Surrounds basal
(13.8)
ganglia
 Commissural fibers
• Connect hemispheres
• Corpus callosum

(13.8)
 Short association fibers
• Connect neighboring areas within
a lobe

(13.13a)
 Long association fibers
• Connect lobes
• Stay within a hemisphere

(13.13a)
 Projection fibers
• Connect cortex with subcortical
sites
• Ascending sensory fibers
• Descending motor fibers

(13.14a,13.13b)
 Basal ganglia

• Deep nuclei of the

telencephalon
(cerebrum):
caudate nucleus,
putamen, globus
pallidus
• Substantia nigra
(midbrain)
(13.13b)
 Basal ganglia

• Functions – regulate movement

• Damage – dyskinesias, disorders of
movement
• Parkinson’s disease – lack of movement,
resting tremor, shuffling gait
• PD video:
http://sprojects.mmip.mcgill.ca/gait/parkinson/movie1.asp

(13.13b)
1. Corona radiata 2. Head of caudate nucleus 3. Body of caudate
nucleus 4. Tail of caudate nucleus 5. Anterior thalamic peduncle 6.
Stria terminalis 7. Anterior nuclear group of thalamus 8. Dorsal
lateral thalamic nucleus 9. Stria medullaris thalami 10. Habenular
nucleus 11. Pulvinar 12. Mamillothalamic fasciculus 13. Anterior
(rostral) commissure 14. Column of fornix 15. Hypothalamic nuclei
16. Substantia nigra 17. Red nucleus 18. Habenulo-interpeduncular
tract 19. Temporal pole 20. Optic tract 21. Mamillary body 22.
Interpeduncular nucleus 23. Medial lemniscus 24. Median section of
pons 25. Lower lip of parieto-occipital sulcus 26. Cuneus 27.
Calcarine sulcus
1. Corona radiata 2. Sagittal stratum 3. Head of caudate nucleus 4.
Body of caudate nucleus 5. Tail of caudate nucleus 6. Connecting
piece between lentiform nucleus and taiI of caudate nucleus 7.
Amygdaloid body 8. Anterior commissure 9. Stria terminalis 10.
Internal capsule 11. Cut surface of basis pedunculi